JPH03157B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a laser processing device for processing ceramic wiring boards, etc. using a laser beam. The present invention relates to a laser processing apparatus that performs secondary processing without moving a workpiece by moving a spot on a plane to a desired position on a plane.

(Prior Art) Such laser processing devices can be roughly divided into two types. The first method is to fix the position of the laser spot and process the workpiece by moving it on a moving stage such as an XY table according to the processing pattern relative to the fixed spot position. On the other hand, the second method is a method in which the position of the workpiece is fixed and the laser spot is moved with respect to the fixed position of the workpiece using an optical path changing element such as a mirror. It is. The first method is capable of machining a wide area of the workpiece, and the second method is capable of machining a small area of the workpiece, but compared to the first method, the moving mechanism part can be machined. Because it is not affected by the weight of the object,
It has the advantage that higher speed processing can be performed and the space of the entire device can be reduced.
For this reason, laser processing equipment that processes wiring such as ceramic wiring boards generally has a second
method is adopted. This second method is called a beam scanner method, and there are two other methods: a galvano scanner and an XY scanner.

The principle of the galvanometer scanner is explained based on FIG. 3. This device consists of a galvanometer 1 and a rotating reflecting mirror 2 connected to the galvanometer.
A galvanometer 3 and a reflecting mirror 4 connected to the galvanometer 3 and rotating around a rotation axis orthogonal to the reflecting mirror 2 are arranged so that the beam remains on a plane at a constant distance even if the incident angle with respect to the optical axis changes. It is composed of a condensing lens, a so-called fθ lens 5, that focuses the . That is, the reflecting mirror 2 receives a laser beam output from a laser oscillator, the rotation angle of which is controlled by the galvanometer 1, the laser beam is scanned in the X direction, and transmitted to the reflecting mirror 4.

The reflection mirror 4 is controlled to rotate in a direction perpendicular to the reflection mirror 2 by a galvanometer 3, and the laser beam is scanned in the Y direction and transmitted to the fθ lens 5. fθ
The lens 5 focuses the laser beam scanned in the X and Y directions by the reflecting mirrors 1 and 2 onto the surface of the workpiece 6 to perform processing. This mechanism has small inertia of the moving parts and is suitable for high-speed machining.

(Problem to be solved by the invention) However, since the rotation angle of the galvanometers 1 and 3 during processing is small (3 to 4.5 degrees), it is difficult to attach a position correction device such as an encoder to improve reproducibility. However, there is a drawback that the desired positioning accuracy cannot be obtained.

SUMMARY OF THE INVENTION The present invention aims to eliminate the above-mentioned conventional drawbacks and provide a laser processing apparatus that can perform laser processing at high speed and with high precision.

(Means for Solving the Problems) The laser processing apparatus of the present invention includes a laser beam generating device, an optical path changing element for changing the beam path of the laser, a driving device for driving the element, and a laser beam spot changing device. The workpiece is machined by scanning a laser beam spot in a two-dimensional direction by an optical path changing element driven by the drive device, and processing the workpiece. In the laser processing device, the driving device is a translational movement mechanism that performs translational driving, and the driving device is further coupled to an arm member fixed to a reflecting mirror via a link mechanism, so that the translational movement by the driving device is caused by the translational movement of the arm member. The driving device is characterized in that the driving device is provided with an encoder that detects the amount of movement and provides feedback for positioning.

(Function) According to the present invention, the drive device for driving the optical path changing element is a translational movement mechanism, and the translational movement of the translational movement mechanism is caused by the angular displacement of the arm member fixed to the reflection mirror by the link mechanism. Since the configuration is such that the angular displacement of the reflecting mirror is converted into the angular displacement of the reflecting mirror to drive the reflecting mirror, the translational movement can be made larger compared to the small angular displacement of the reflecting mirror, and therefore the position can be finely adjusted. Can be done. Furthermore, by disposing an encoder in the translational movement mechanism, errors in position control are compensated for, and the reproducibility of the laser beam spot is improved.

Furthermore, by appropriately changing the length of the arm member and the length from the reflecting mirror to the workpiece, the accuracy of the translation mechanism can be changed by the ratio of these, and by setting this ratio to an appropriate value. ,
Processing accuracy can be increased.

(Example) Embodiments of the present invention will be described based on the drawings.

FIG. 1 shows an example of a laser processing apparatus according to the present invention. In this figure, for clarity of explanation, we will explain the case where the laser beam is scanned in one-dimensional direction, that is, the spot of the laser beam is scanned in one-dimensional direction by driving the reflecting mirror in the X-axis or Y-axis direction. do. However, it is intended that spot scanning in two-dimensional directions can be easily understood from now on.

11 is a laser beam generator, 13 is a reflection mirror that reflects the laser beam, 15 is a step motor that drives the reflection mirror 13, 17 is a workpiece that is scanned by the laser beam spot,
For example, ceramic wiring boards are shown.

A ball screw 23 is connected to the shaft 19 of the step motor 15 via a coupling 21, and this ball screw 23 converts the rotational motion of the step motor 15 into translational motion.

A rod 25 is provided on the ball screw 23, and this rod 25 is connected to the arm 2 through a link mechanism.
It is connected to 7. This link mechanism connects the ball pin 29 provided at the tip of the rod 25 to the arm 27.
It is constructed by fitting into a long groove 30 provided at one end of the .

In this link mechanism, the ball pin 29 slides within the long groove 30 in response to the translational movement of the rod 25, thereby ensuring the translational movement of the rod 25. The other end of the arm 27 is fixed to a reflecting mirror 13, and the reflecting mirror 13 is disposed such that its center is rotatable about an axis 31 perpendicular to the plane of the drawing. Therefore, when the ball pin 29 slides in the long groove 30 as the rod 25 translates, the arm 27 swings around the shaft 31. Therefore, the reflecting mirror 13 fixed to the other end of the arm 27 swings about the shaft 31.

By the way, the step motor 15 is provided with a rotary encoder 33.
The encoder 33 outputs a pulse proportional to the rotation angle of the input shaft, and this output is fed back to the step motor 15 so that the rotation angle of the step motor 15 can be corrected by a known control circuit. This encoder 33 is essential for more accurate positioning.

The operation of the laser processing apparatus configured as described above will be explained below.

When the step motor 15 rotates to a predetermined rotation angle, this rotation is transmitted to the ball screw 23 via the coupling 21, and the ball screw 23 translates the rod 25 in minute units according to the rotation angle of the motor. let The translational movement of the rod 25 is ensured by a link mechanism composed of a ball pin 29 and a long groove 30, while ensuring the translational movement of the rod 25.
Together with the shaft 31, this results in an angular displacement of the arm 27, and this angular displacement can rotate the reflecting mirror 13 and scan the spot of the laser beam 73 from the laser beam generator 11 in the X-axis or Y-axis direction. .

Incidentally, the step motor 15 is controlled in a semi-closed loop by the rotary encoder 33, and errors in the rotation angle of the motor are compensated for, but thermal expansion of the rod 25 and arm 27, errors in the ball screw, and link mechanism Although the error still remains, the accuracy can be changed by the ratio of the distance L ₁ from the optical axis to the translation axis to the distance L ₂ from the optical axis to the workpiece.

For example, step motor 15 and ball screw 2
If L ₁ :L ₂ =10:1 allows for translational movement with an accuracy of 1 μ by 3, the workpiece can be scanned with an accuracy of 0.1 μ.

An example of the laser processing apparatus of the present invention has been described above, and as a modification of this laser processing apparatus, a case will be described in which a linear motor is used as the drive device.

FIG. 2 shows a schematic diagram of a modified example. The difference between this modification and the device shown in Fig. 1 is that the linear motor 5
5 and its positioning devices, linear encoders 61, 63, 65, have replaced step motors and rotary encoders. Furthermore, the link mechanism has been changed from a ball pin and long groove to a linear ball bearing 67.

First, to briefly explain the structure of this modification, the shaft 59 extends from the linear motor 55 and moves in translation by the drive of the linear motor 55.
A slit plate 61 in which slits are made at regular intervals is provided in the middle part, and a light emitting diode (LED) 63 is arranged on one surface side of this slit plate 61, and a photodiode is arranged on the opposite surface side. A transistor (PT) or a photodiode (PD) 65 is provided, and the phototransistor 65 reads out the light from the light emitting diode 63 that has passed through the slit plate 61, counts the amount of movement, and controls the signal in feedback.

The end of the shaft 59 is rotatably attached to a linear ball bearing 67 that slides on an arm 69, and the arm 69 is fixed to a reflection mirror 53, which is rotatable about an axis 71. be. Therefore, by the same operation as in the first embodiment, the translational motion of the shaft 59 is converted into a swinging motion of the arm 69, which in turn is converted into a swinging motion of the reflecting mirror 53. Note that 51 is a laser beam generator, and 57 is a workpiece scanned by the laser beam spot.

To briefly explain the operation of the modified example configured in this way, the shaft 59 is driven by the linear motor 55.
is translated by a predetermined amount, and this translational movement is converted into a rotational movement about the axis 71 of the reflecting mirror 53 of the arm 69 by the linear ball bearing 67, resulting in a rotational movement of the reflecting mirror 53, and the laser beam generator 51 beam to this reflecting mirror 53
The workpiece 57 can be scanned in a one-dimensional direction by being reflected by the beam. This modification differs from the embodiment shown in FIG. 1 in that the rotational movement of the motor can be omitted by using a linear motor, which contributes to higher accuracy.

Further, the amount of translational movement is detected by the photoelectric linear encoders 61, 63, 65, and fed back to the linear motor 55.
To efficiently move a shaft 59. For example, if the linear motor 55 is controlled to accelerate or decelerate using a trapecloid curve, high-speed positioning without residual vibration or overshoot can be performed. Further, the change in accuracy is the same as the explanation regarding FIG. 1.

Above, an example has been described in which the laser processing device of the present invention scans the surface of a workpiece in one dimension. However, in order to scan the laser processing device in a two-dimensional direction, it is necessary to separate By arranging the devices appropriately, each of these reflecting mirrors is
2 by rotating in the axial and Y-axis directions.
Dimensional scanning is easily accomplished.

(Effects of the Invention) According to the laser processing apparatus of the present invention, the driving device for translational movement drives the reflecting mirror via the translational-oscillation motion conversion mechanism, and the driving device is equipped with an encoder, thereby achieving a semi-closed state. Loop control improves accuracy and enables high-speed machining comparable to galvanometer methods.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a laser processing apparatus of the present invention, FIG. 2 is a schematic diagram showing a modification of the embodiment shown in FIG. 1, and FIG. 3 is an explanatory diagram showing the principle of a conventional galvano scanner. . 11,51...Laser beam generator, 13,5
3...Reflection mirror, 15...Step motor, 17,5
7... Workpiece, 19, 59... Shaft, 21... Coupling, 23... Ball screw, 25... Rod,
27, 69... Arm, 29... Ball pin, 30... Long groove, 31, 71... Shaft, 33... Rotary encoder, 73... Laser beam, 55... Linear motor,
61...Slit plate, 63...Light emitting diode, 65
...Phototransistor, 67...Linear ball bearing.

Claims (1)

[Claims] 1. A laser beam generator, an optical path changing element that changes the beam path of the laser, a driving device that drives the element, an optical system that forms a spot of the laser beam, and a workpiece. and a mounting table for placing the
In a laser processing device that processes a workpiece by scanning a spot of a laser beam in two-dimensional directions with an optical path changing element driven by the drive device, the drive device is a translational movement mechanism that performs translational drive, and further the driving device is coupled to an arm member fixed to the reflective mirror via a linkage mechanism so that translational movement by the driving device is converted into an angular displacement of the arm member, resulting in an angular displacement of the reflective mirror; A laser processing device characterized in that the drive device is provided with an encoder that detects the amount of movement and provides feedback for positioning.